The human may exchange much information through non-language means (hereinafter referred to as gestures) such as the expression of a face, the motions of hands, the directions of eyes and the motion of a head. If an information exchange scheme using a gesture is applied to a Human-Robot Interaction (HRI) technology, a human-friendly HRI technology may be better implemented. In this viewpoint, a gesture recognition technology is one of technologies that are attracting much attention, in the HRI technology.
The gesture recognition technology is categorized into a sensor-based gesture recognition technology that attaches sensors to the human body and a vision-based gesture recognition technology using a video camera, according to methods for acquiring data. Among these technologies, the vision-based gesture recognition technology is classified into Two-Dimensional (2D) or Three-Dimensional (3D) recognition according to the dimension of input data, or is classified into the recognition of hand motions, the recognition of an upper body and the recognition of body motions according to a body range for recognition.
An HRI technology based on the existing gesture recognition technology has restrictions below in a gesture recognition method for interaction between a robot and a human in a long distance.
First, existing technologies cannot provide a meaning gesture for interaction between a robot and a human and a method for recognizing the meaning gesture, in a long distance. That is, the existing technologies recognize only hand motions in a near distance, and further focus on recognition based on the recognition of an upper body and body motions than interaction between a robot and a human in a long distance. Accordingly, an attempt is not almost made on vision-based gesture recognition for HRI, in a long distance.
Second, the existing technologies require the input video of high resolution for recognizing the upper body or body gesture of a human that is in a long distance, or require two or more cameras and devices corresponding to them for obtaining 3D information. Accordingly, it is difficult to implement a low-cost system that is configured with a single camera.
Third, in a case of using only a single camera, the existing technologies mostly fix cameras for easily extracting input videos. Accordingly, it is difficult to apply the HRI technology based on a gesture recognition technology to a robot platform in which cameras move.
Fourth, the existing technologies require many restrictions to users for securing the stability of a system that recognizes gestures. For example, for allowing a system to know the start time and end time of a gesture, users mainly wear auxiliary items such as gloves and clothes having specific colors. However, it is difficult to expect the users to give the above-described cooperation for the stability of recognition, in a daily robot service environment where users behave freely.
Accordingly, the existing HRI technology based on a gesture recognition technology has limitations in providing a meaning gesture recognition method for interaction between a robot and a human in a long distance.